#include<bits/stdc++.h>

using namespace std;

int main() {
    cerr << 1 / 2 << endl;//0
    int n;
    while (cin >> n) {
        double s = 0;
        //s=1/1+1/2+...+1/n;
        for (int i = 1; i <= n; i++) {
            s = s + 1.0 / (double) i;
        }


        printf("%.3f\n", s);
    }


    return 0;
}
